1. Field of the Invention
The present invention relates to a search method and circuit therefor, which can search a certain predetermined part of a tape, and more particularly to a search method and circuit utilizing an audio signal, which can record on the audio track specific audio signals having a frequency above the audio frequency yet within the audio range of image processing systems and sound instruments such as VCRs, camcorders (Movie Camera) and the like, and can ascertain a desired position quickly by detecting the specific audio signal upon selection of a search mode by an operator.
2. Description of the Prior Art
Generally, the search method applied by conventional image processing systems utilizes a duty ratio of control pulses that are recorded in a tape control track and that are recorded differently from normal information signals. Thus, conventional processing systems would search for a tape location recorded with a different duty ratio of control pulses during the execution of a search operation. A conventional search method applied to prior art sound instruments detected an unrecorded portion between recorded selections.
However, the conventional method of ascertaining the desired tape location by recording different duty ratios of control pulses is impractical in that it requires a complicated circuit construction. Specifically, a circuit that detects control pulses must be constructed for finding a location having a different duty ratio. Also a circuit must be provided which causes changes in duty ratio of control pulses. In the case of sound instruments, the method of finding the desired location by utilizing unrecorded portions between recordings has a drawback in that only the first part or end part of a song can be searched and the middle of a song cannot be searched. In addition, if there is a long period of recess in the middle of a song, this portion can be mis-read as an unrecorded portion, in which case incorrect operation results.